30 BUILD REPORT:
The Quest for a Different
Kind of Flipper: Making
the Machine
by Zac O’Donnell

33 Then and Now —
A Decade Later With
Jim Smentowski
by Kevin M. Berry

35 EVENT REPORT:
RoboGames 2013
by Ray Billings

39 PRODUCT REVIEW:
HobbyKing HK4B6
Charger
by Pete Smith

39 CARTOON

40 RESOURCE REVIEW:
MFG.com
by Mike Jeffries

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30 SERVO 07.2013

BUILD REPORT:

The Quest for a Different Kind of
Flipper: Making the Machine

● by Zac O’Donnell

In last month’s issue of SERVO,
I wrote about my
six pound flywheel-powered flipping
robot named
Threecoil. I
focused on the
new design for
the trigger
mechanism, and
the iterations of
testing and
redesign that it
went through
before competing
for the first time.

This month, I will discuss the
fabrication of some of the parts
that made up the flipper
assembly in Threecoil.

In Figure 1, you can see the
pile of metal that started it all.
The large aluminum tube was
used for the coil drum, and the
solid aluminum round was used
for the flywheel and coil drum
end caps. One of the small steel

FIGURE 1.
Metal stock.

FIGURE 2. Finished rings.

rings was used for the flywheel,
and the channel and flat bar
stock were used for the arm.